Help me please: I have suspension mods but still feels meh

[SteveW]

Until you put performance pack bracing it will drive like a wet noodle no matter what you do with tires.

I agree with this. You can't go wrong by adding this bracing. @SDAMike Do this next then go from there.

I don't think the rest of your setup is out of whack for a street car but may need fine tuning like:

Lower tire pressures from 40 to what others have recommended.

Reset the shocks to full soft and adjust one end of the car at a time until you feel it getting bouncy or springy then back off a 1/4 turn. If you continue going stiffer the ride will get harsh and you may lose traction completely over bumps while turning. Adjusting one end of the car at a time will help you feel more clearly what the changes do to your ride and handling. Also, the front shock settings will likely be different from works for the rear.

Alignment could be contributing to poor handling but if you really have it set to BMR's settings that should be ok.

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[Norm Peterson]

I've never been a fan of lowering a car more in the front if I am dropping to help handling. It changes the weight distribution. A front engine car is already biased toward more front weight. From my Honda days I had a set of adjustable coilovers. You could definitely feel the difference between having the back higher and keeping it level. The level car felt more neutral. A lot of cars these days have a bigger fender gap in the front, so aftermarket manufacturers try to give the best looking solution by dropping the front a bit more to even things up. That raked look is probably as old as hot rodding itself. It just looks good. Some kits however have an even drop. That would probably be my choice. But hey I'm not a pro, just my observations.

It's really not the rake that affects the handling, it's because lowering the car also changes the roll center heights and that's what affects handling feel.

Changing the rake to more nose down only makes a minor change in the front to rear weight distribution, I think on the order of a quarter of a percent or less in most cases (think 54/46 to 54.2/45.8).


Norm

 

[GT 550]

OP it doesn't appear that you're running either spherical shock mounts at the rear or RLCA upgraded bushings/bearings. Improvements from both are well documented in the Suspension thread, probably worth researching to see if the problems described match yours. I found both made a difference but by far the most noticeable was changing out the RLCA bushing for a Steeda bearing although I'd now use an upgraded SuperPro bushing instead. Car was awful at the rear in corners particularly if the surface was uneven, felt like it was all over the place but now it's nicely stable.

 

[TeeLew]

It's really not the rake that affects the handling, it's because lowering the car also changes the roll center heights and that's what affects handling feel.

Changing the rake to more nose down only makes a minor change in the front to rear weight distribution, I think on the order of a quarter of a percent or less in most cases (think 54/46 to 54.2/45.8).

You had it right to start with roll centers. Rake (within reason) doesn't change weight distribution. If it did, a 1/2% shift would be noticeable.

 

[Norm Peterson]

Im not sure if this changes anyone's thoughts or recommendations but I actually have 285/35's, not 285/40's. I remembered wrong, duh. I just double checked after mentions of rubbing (which I have never had) and being to tall I knew I used a tire calculator to make sure I was the same overall diameter as the 255/40's that were on the car stock and the 285/35's are actually .1" shorter.

No particular changes from me. It's still a min-recommended fitment that will favor ride quality at some hopefully minimal cost in terms of response and precision.


Norm

 

[TeeLew]

Honestly, I don't know where you guys are coming from when you say a stock Mustang is so difficult to control. I drive all sorts of rental cars. They're all base models & have been beat up. None of them are any big deal to drive hard.

 

[NightmareMoon]

But man you nailed it with "I had no idea what it was going to do. It felt like rear was wiggling. Not confidence inspiring at all"

This makes me really wish you'd check the rear hubs for play. Wiggling at speed is what my car did when the hubs were shot. Unpredictable was the work I'd use to describe it too.

The other time I had 'unpredictable' handling, a different suspension bolt had fallen off. Sitting here wondering why my car is behaving strangely/inconsistently and I didn't have all the fasteners in the front suspension. A different time than that and I had a control arm bearing that went out and developed some play. BOY that was hard to track down, but an alignment tech noticed after our 2nd attempt to get the alignment sorted (it wouldn't drive straight when the alignment machine said it was good) it and I'm super grateful he caught that. Same check for loose wheel hubs would have caught that one too.

SO... It would really be a good idea to go ahead and take the car to a performance shop and have them check all the suspension bits, HUBs, control arms, etc for play. I'd really like to rule out a mechanical issue before you go crazy trying 15 different internet suggestions to solve your issue.

There are a lot of fun suggestions in this thread. NONE of them will solve you problems if you have a defective hub or other mechanical problem.

 

[GT 550]

@NightmareMoon great advice given the issues we have with hubs.

 

[bnightstar]

This makes me really wish you'd check the rear hubs for play. Wiggling at speed is what my car did when the hubs were shot. Unpredictable was the work I'd use to describe it too.

You will hear this though.

I suggest he start with a real good alignment this cars from the factory have terrible alignment that is a crime.
Then if an alignment didn't solve the issue he can check hubs etc.

But you are spot on with the hubs Idea. When mine were shot my car wiggled over bumps in the back and was annoying as hell. Drivable but annoying.

 

[Norm Peterson]

Checking the hubs should be part of the preliminaries before ever touching the suspension with a wrench for alignment purposes. Just like checking and adjusting the tire pressures is. Any hub looseness means that whatever settings you make won't stay put and will probably change just by driving the car off of the alignment rack.


Norm

 

[Genxer]

It's really not the rake that affects the handling, it's because lowering the car also changes the roll center heights and that's what affects handling feel.

Changing the rake to more nose down only makes a minor change in the front to rear weight distribution, I think on the order of a quarter of a percent or less in most cases (think 54/46 to 54.2/45.8).


Norm

Interesting, thanks for the info. I knew changing heights did something to the car, maybe just not completely understanding the physics of it.

If and when I make any changes, think I’ll be leaning toward a kitted approach such as matched springs/dampers and a very slight drop (street use).

 

[SDAMike]

The car has 6,000 miles, most of that is highway driving, hubs go bad that fast?

 

[SDAMike]

Honestly, I don't know where you guys are coming from when you say a stock Mustang is so difficult to control. I drive all sorts of rental cars. They're all base models & have been beat up. None of them are any big deal to drive hard.

I dont think difficult to control is the right phrase. I would say "feels unpredictable" or "hard to establish the limit".

Especially compared to any other sports car I have ever owned. Granted I went directly from a 2018 GTI autobahn to a non PP Mustang GT, and before that I had a E46 M3, so my views may be a bit skewed.

 

[SDAMike]

I agree with this. You can't go wrong by adding this bracing. @SDAMike Do this next then go from there.

I don't think the rest of your setup is out of whack for a street car but may need fine tuning like:

Lower tire pressures from 40 to what others have recommended.

Reset the shocks to full soft and adjust one end of the car at a time until you feel it getting bouncy or springy then back off a 1/4 turn. If you continue going stiffer the ride will get harsh and you may lose traction completely over bumps while turning. Adjusting one end of the car at a time will help you feel more clearly what the changes do to your ride and handling. Also, the front shock settings will likely be different from works for the rear.

Alignment could be contributing to poor handling but if you really have it set to BMR's settings that should be ok.

I hear ya and I plan on doing the bracing up front. Do both of you mean extra bracing out back too? I do have the CB005, should I be adding the steeda IRS braces or the BMR CB762 also?

 

[SDAMike]

OP it doesn't appear that you're running either spherical shock mounts at the rear or RLCA upgraded bushings/bearings. Improvements from both are well documented in the Suspension thread, probably worth researching to see if the problems described match yours. I found both made a difference but by far the most noticeable was changing out the RLCA bushing for a Steeda bearing although I'd now use an upgraded SuperPro bushing instead. Car was awful at the rear in corners particularly if the surface was uneven, felt like it was all over the place but now it's nicely stable.

I do have the steeda rear shock mounts. I'll look into the RLCA's though, is that the one that needs to be pressed in like by a shop? Curious, why do you say you would do the superpro bushing instead?

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